Traditionally, organizations such as corporations hosted computing devices like servers at locations under the control of the organizations. For example, a company may have purchased or leased a number of servers, and located them in a server room at the same location as the company's other assets, including its human resources, or at an offsite location under the control of the company. However, computing needs can be variable, which means that many times organizations have had to purchase or lease more servers than what they typically needed, to accommodate peak utilization.
More recently, cloud computing topologies such as infrastructure as a service (IaaS) and platform as a service (PaaS) have become available. An organization may be able to rent or lease a portion of a computing device like a server, or the complete computing device, for a period of time ranging from days to weeks or even months or longer. The computing device remains physically located at the facilities of a service provider, and a company or other customer of the provider accesses the device over the Internet. This means that the company can more closely size the computing resources it leases with the company's current computing needs.